Huisman Method I Drawdown
Huisman Method I Drawdown Calculation
See Also:
This method calculates the difference in the drawdown that would occur if a pumping well and observation well did not fully penetrate an aquifer. It is used for confined aquifers that have been pumped to steady state conditions. The method uses the equation:
Values in the equation are shown below:
where:
Spartial = observed steady state drawdown
Sfull = steady state drawdown that would have occurred if the well had been fully penetrating
Zw = distance from the bottom of the well screen to the underlying aquiclude
b = distance from the top of the well screen to the underlying aquiclude
Z = distance from the middle of the observation well screen to the underlying aquiclude
d = length of the well screen
D = aquifer thickness
Q = pumping rate
K = aquifer hydraulic conductivity
r = radial distance from the pumping well to the observation well
The summation is continued until n = 6. The effect of additional summations is negligible.
Output:
The following values are displayed as the results
The difference in drawdown from partial penetration and full penetration.
The value of the term behind the summation continued until n = 6
The penetration ratio, d/D
The amount of eccentricity l/D, where l is the positive distance between the middle of the pumping well screen and the middle of the aquifer